LM2576: unstable output

Technical Scandia

Part Number: LM2576

I'm using an LM2576S-5.0/NOPB to implement a buck converter, my load draws around 1A on worst case.

The step down was designed with an inductor of 100uH and a capacitor of 330uF, the output is unstable and use a large capacitor(2000uF) doesn't fix the problem.

this image is the output without load.

over 2 years ago

0 Frank De Stasi over 2 years ago

TI__Guru 57555 points

Hello

Can you send you schematic and a picture of your PCB layout layers and silk screen.

At what node are you taking the image?? Is it the OUT of the device or the +5Vout of the regulator??

What load are you using in the image??

Is the output voltage regulated at +5V ???

Thanks

0 Technical Scandia over 2 years ago in reply to Frank De Stasi

Prodigy 10 points

Hi Frank,

was taken in the node J4, is the already regulated out.

without load, when I tried to put a load to test, this one burns before I can take another picture.

the multimeter shows +5v without load, drops inmediatly if the load is connected.

0 Frank De Stasi over 2 years ago in reply to Technical Scandia

TI__Guru 57555 points

Hello

This looks like a layout issue.

Please send images of your PCB layout.

Also, please look at the PCB layout in the data sheet and try to follow that layout.

You can also get an EVM for this device and test.

Thanks

0 Frank De Stasi over 2 years ago in reply to Frank De Stasi

TI__Guru 57555 points

Hello

I will close this post due to inactivity

If you need more help, you can re-open.

Thanks

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LM2576: unstable output